ARISTOTLE

• Aristotle's views on physical science profoundly shaped medieval scholarship.
• He believed all peoples' concepts and all of their knowledge was ultimately based on perception.
• He was a Greek philosopher born in Stagirus, northern Greece
• He joined Plato's Academy in Athens
• 383-322 he was alive

ARISTARCHUS

• Alive from 310 – c. 230
• Greek astronomer and mathematician
• Attempted to measure the relative distance between sun and moon
• Used geometry to solve scientific problems

PTOLEMY

• Alive from 100-170 CE
• Astronomer, geographer, and mathematician
• Believed planets moved in small circles
• Allowed predictions of the motion of planets for the future
• Planets moved backwards in the sky

NICOLAUS COPERNICUS

• Alive from 1473-1543
• Developed first detailed model of the solar system
• Said planetary paths should be perfect circles
• Came up with heliocentric model
• Used circular orbit

JOHANENES KEPLER

• Alive from 1571-1630
• German mathematician wand astronomer
• Discovered planetary movements did not fit perfectly
• Made Kepler's laws

Kepler's first law

Elliptical orbits: planets orbit in an ellipse with the sun at one focus

Kepler's second law

Equal areas and equal times

Planets sweep out equal areas at equal times

-at perihelion- the planet is moving faster

-at aphelion- planet sweep out a long narrow area

Kepler's third Law

The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit

Helpful terms:
Aphelion: point where an object is furthest from the sun

Perihelion: point where object is closest to sun

Eccentricity: the amount deviated from a circle

GALILEO GALILEI

• Alive from 1564-1642
• Scientist
• Made innovations to the telescope
• Observed moons

ISAAC NEWTON

• 25 December 1642 – 20 March 1727
• Newton's Principia formulated the laws of motion and universal gravitation
• Newton built the first practical reflecting telescope

EDWIN HUBBLE

• Born: November 20, 1889 Died: September 28, 1953
• Astronomer
• Invented the Hubble telescope
• regarded as one of the most important observational cosmologists

GEOCENTRIC MODEL
the geocentric model is a description of the cosmos where Earth is at the orbital center of all celestial bodies.

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